#include<stdio.h>
int main()
{
	int number;
	int sum=0;
	int count=0;
	scanf("%d",&number);
    while (number!=-1) {
			sum+=number;
			count ++;
			printf("sum=%d,count=%d\n",sum,count);
			scanf("%d",&number);
		}
	printf("%f\n",1.0*sum/count);
	return 0;
}
